This invention relates to a fully rotary type scroll fluid machine in which a driving scroll and a driven scroll are rotated.
In general, a kind of volume type compressor in which a pair of spiral protrusions are operated for compression, namely, a scroll compressor is extensively employed as a scroll fluid machine of this type.
The operating principle of the scroll compressor is generally as follows: As disclosed by the specifications of U.S. Pat. Nos. 3,884,599 and 2,475,247, one of the spiral protrusion is rocked with the other fixed, to achieve compression.
A so-called "fully-rotary type scroll compressor", in which the spiral protrusions are rotated around their own axes, is also well known in the art over the above-described U.S. Patents.
The operating principle of the fully-rotary type scroll compressor will be described. As shown in FIG. 22, a driving scroll 1 is rotated around its axis O.sub.1 by means of a drive source such as an electric motor, engine or turbine, while a driven scroll 2 is also rotated around its axis O.sub.2 in synchronization with the rotation of the driving scroll 1. As the scrolls are rotated in this manner, a compression chamber 3 formed between the spiral protrusions 1a and 2a of the scrolls 1 and 2 decreases its volume while moving towards the center, thus compressing the gas therein. The gas thus compressed is discharged, as high-pressure gas, through a discharge outlet 2c. The part (a) of FIG. 22 shows the scrolls turns through 0.degree.; that is, it shows that gas is sucked into the compression chamber 3. While the scrolls are turned 0.degree.--90.degree.--180.degree.--270.degree.--360.degree. (0.degree.) as shown in the parts (a) through (d) of FIG. 22, the compression chamber 3 decreases its volume while moving towards the center. It should be noted that, during this period, sealing parts S formed by the spiral protrusions 1a and 2a of the scrolls 1 and 2 are maintained aligned in a diametrical direction of the scroll compressor.
In the scroll compressor, the torque of the driving scroll 1 is transmitted to the driven scroll 2 as follows: As described in the specification of the aforementioned U.S. Pat. No. 2,475,247, a coupling (not shown) through which the driving scroll and the driven scroll are coupled to each other is provided on the side of their central axes in such a manner that it is movable in an X-Y direction; or as described in the specification of the aforementioned U.S. Pat. No. 3,884,599, a coupling (not shown) is disposed between the scrolls 1 and 2 in such a manner as to extend over the diameter of the scroll compressor.
As was described above, in the conventional scroll fluid machine, the coupling is arranged between the two scrolls. Therefore, in the case where one of the two scrolls, after being connected to the coupling, is combined with the other, the coupling is covered by the other scroll. As a result, it is considerably difficult to position the scrolls and the coupling thereby to assemble them; that is, the assembling work of the coupling is troublesome.
On the other hand, as the coupling wears, the abrasion powder is liable to be caught directly between the spiral protrusions thereby to accelerate the abrasion of the latter; that is, the sealing ability of the spiral protrusions is lowered in a short period. As a result, in the case of a compressor, the compression efficiency is lowered; and in the case of a vacuum pump, the degree of vacuum is decreased. Furthermore, when the coupling has been worn out, it is necessary to remove the scrolls from the machine. That is, the conventional scroll fluid machine is low in maintenance.
In view of the foregoing, an object of this invention is to provide a scroll fluid machine in which the assembling work of the coupling and the maintenance can be achieved readily, and the sealing ability of the spiral protrusions can be maintained unchanged for a long period.